Thermal management of lithium ion batteries is a crucial challenge as mobility becomes a key factor in the design systems ranging from high performance electronic devices to consumer and entertainment products. From a thermal perspective, the combination of high density of interfaces, limited heat dissipation paths, and heterogeneous material systems provides a significant challenge in ensuring safe operation in all environments. Here, we focus on evaluating thermal transport within lithium ion battery cells using a combination of high resolution infrared thermography and associated thermal models. In particular, we measure the effective thermal conductivity of the anode-separator-cathode stacks in 18650 battery cells with and without the presence of electrolytes. Preliminary results without electrolyte demonstrate the effectiveness of the measurement technique, but the electrolyte is expected to significantly impact thermal transport within the system. Ultimately, these results can be integrated into models of thermal transport in lithium ion battery cells in order to improve device performance, safety, and reliability.